DESCRIPTION: The overall goal of the project has been to understand the role of calcium activated proteolysis in normal lens and lenses undergoing cataractogenesis. The current application concentrates on providing a detailed mechanism for activation of calpain II in lens through three aims: Aim 1 will characterize the sequence of the active form of calpain II in lens and consider the possible translocation and activation of calpain II on lens membranes. Aim 2 will characterize the influence of specific components of the lens insoluble fraction on calpain II activation. Specifically the influence of lens membrane components will be evaluated and the localization of calpain II to the insoluble pellet will be studied. A proteinaceous activator for calpain II in lens will be considered. Aim 3 will determine the influence of mRNA expression on calpain II activity in lens by measuring expression of calpain II mRNA.